The invention relates to a digital shift register which utilizes tunnel diodes in the interstage coupling circuitry connecting successive latches.
Resonant-tunneling diodes (RTDs), because of their very high ratio of Current density to specific capacitance, are capable of switching extremely rapidly. For example, oscillators have been configured which operate above 700 GHz. Building complex logic circuits from two-terminal devices, however, poses a greater challenge. For one thing, the devices have to switch over a wide voltage range and cannot be restricted to the highest speed part of their operating range. For another, the same terminal has to be used as both the input and the output, making isolation a problem. The present invention provides a new approach for realizing a digital shift register using RTDs that is expected, based on simulations, to reach speeds in the 50 GHz range with low power consumption. The circuit requires few component types, e.g., tunnel diodes (TDs) and Schottky diodes only, provides relatively wide operating margins, and is capable of fan-in and fan-out operations.